In this specification unless the contrary is expressly stated, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned.
The term “prismatic glass” used herein is glass with machined surfaces of relatively large area and optically flat but polished to generate a prismatic effect. The prisms refract light rays and change their direction.
The use of prismatic glass in architectural and design applications began in the late 19th century with the introduction of prismatic glass transoms, also known as prismatic transom windows, which provided a practical means of directing sunlight into building interiors. With origins in sidewalk vault lights and glass panels used on ship decks, the prismatic tiles used in these windows included ridges, or similar raised patterns, on their inside surface that refracted incident sunlight toward the rear of a building. Varying designs of prismatic glass tiles were developed in an attempt to increase natural light levels within buildings, and thereby reduce reliance on artificial light sources. The use of prismatic glass tiles, especially in storefronts, was prominent until about the 1930s when the dominance of electrical light sources led to their functional obsolescence.
In more recent times, prismatic glass laminates have become desirable as decorative architectural elements in both interior and exterior applications. A basic prismatic glass laminate will include some form of faceted glass applied or affixed to an underlying substrate, which allows the laminate to be mounted to a surface. However, many modern architectural applications require that prismatic glass laminates use precision faceted glass and maintain a high degree of structural integrity even when damaged or fractured.
A conventional approach to fabricating a prismatic glass laminate involves affixing a panel of faceted glass to one or more substrate layers using a suitable laminating interlayer. An example of this conventional construction is illustrated in FIGS. 1A and 18 of the drawings. FIG. 1A shows a side view line drawing of a conventional prismatic glass laminate 100, whilst FIG. 1B shows a perspective view line drawing of the same conventional prismatic glass laminate 100. The laminate 100 includes a single prismatic glass element 102 having a number of facets or ridges along its upper surface. The glass element 102 is affixed to a substrate 104 using a suitable laminating interlayer 106 which bonds the glass element 102 to the substrate 104.
Many architectural applications, such as the use of prismatic glass laminates in building windows, require that glass panels be used as the substrate 104 to allow light to enter the building. Glass panel substrates 104 are also used in prismatic glass laminates for many other applications requiring the refraction and reflection of light through many different angles, to achieve a variety of different effects. In particular, glass panel substrates 104 can be used in combination with appropriately shaped prismatic glass elements 102 to achieve the refraction of white light into colours of the visible spectrum which can be observed from one or both sides of the glass laminate. These architectural applications commonly use a laminating interlayer 106 known as polyvinyl-butyral (PVB) which provides a strong bond between the glass element 102 and the substrate 104. The PVB is a resin that provides optical clarity, which is beneficial in applications where the substrate is a glass panel, and flexibility to allow for minor shifts in the position of the glass element 102. However, it should be understood that it is also possible to affix the glass element 102 to any number of building or construction surfaces such as metal, timber, concrete, or plastic, using an alternate laminating interlayer.
Laminating interlayers, such as PVB resin are commonly used in the automotive and architectural industries where it is necessary to bond together two panels of glass, such as automobile windshields and safety glass. This bonding process often takes place under conditions of heat and pressure, which cause the PVB interlayer to become optically clear and bind together the two panels of glass. The primary functions of the laminating interlayer are to retain any resulting shards of glass in the event that the glass pane is fractured, and to maintain a degree of structural integrity of the panel after fracturing.
In spite of the benefits that result from using laminating interlayers, the conventional construction of prismatic glass laminates, such as the laminate shown in FIGS. 1A and 1B, still include a number of significant limitations:                If the faceted surface of the prismatic glass element 102 is required to be machined from float glass, then it is not possible to achieve the required flat and polished surface finish using peripheral wheels. It is also impractical to efficiently operate cup wheels, in a sequential manner, to obtain the desired finish. Similarly, if the prismatic glass element 102 is cast, then the process of grinding and polishing the cast surface involves similar problems to those encountered with float glass.        The lamination of large pieces of manufactured glass is often problematical, as there is a propensity for the glass to crack during the lamination process. This is particularly the case for faceted glass which has substantial variations in thickness and therefore reduced strength in areas where the glass is thinner. Similarly, for cast glass, deviations in the overall flatness of the glass must often be eliminated by machining the flat face prior to lamination.        It is often difficult to toughen or “temper” faceted glass whilst maintaining flatness, due to the significant variations in the thickness of the faceted glass.        If the prismatic glass element 102 is cracked as a result of impact or external stresses, these cracks can propagate to the edges of the glass element and large pieces or shards of glass can become dislodged. Any dislodged shards of glass present a significant danger to persons and/or property at lower elevations.        The overall thickness of the prismatic glass element 102 is generally dictated by the minimum thickness required to prevent fracture of the glass as a result of deflection caused by wind or other loads.        
In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of the common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned.